Prior to the adoption of computers for the purpose of selecting colors to be used in the creation of color images, artists employed a physical palette upon which to place and mix colors used in the image creation process. The individual skill and aptitude of the artist dictated how quickly they would be able to select colors for their palette. Specifically, the degree to which an artist possessed a practical and theoretical knowledge of how colors work together usually dictated how quickly they would be able to select colors for their palette and how quickly and accurately they would be able to mix these selected colors in a manner that ensured they harmonized together when applied to the creation of an image.
An improvement to the manual operation of selecting and mixing colors on a physical palette came with the availability of accurate color charts, such as the charts developed and sold by Pantone, Inc. Unfortunately, these color charts contained hundreds or thousands of colors from which the artist could select to create their palette. Selecting and harmonizing colors from such a large assortment of colors takes quite a bit of time.
With the advent of computers, artists realized that software could be designed that would automatically apply color theory to the color selection process thereby making the process of color selection and harmonization much more efficient as well as accurate. One such application of computer software to the color selection process is disclosed in U.S. Pat. No. 4,794,382 entitled, “Image Retouching”. This patent discusses a two-step method for arriving at an accurate choice of tint that can be used to modify or retouch an existing color in a color image. The first step of the method involves identifying and displaying a coarse range of colors and the second step of the method involves selecting one of the colors in the coarse range and displaying a fine range of colors, centered on the selected color. The coarse range represents a group of colors with adjacent colors differing from each other by more than a predetermined amount. The fine range represents a group of colors with adjacent colors differing from each other by less than the predetermined amount. The color ranges are displayed on a computer monitor as a continuous line of individual colors. The manner that these color ranges are selected is described with reference to FIG. 1. Further, the patent discloses that the characteristics of the color in each of the ranges can be changed. So, for instance, the intensity of the colors can be changed. One of the deficiencies with this method is that the color space that is available from which to select colors is a non-perceptual color space. Non-perceptual color spaces are designed to accommodate the needs of display devices, such as a computer monitor or printer, and as such are not good tools for artists to use when selecting colors for their palette.
U.S. Pat. No. 5,311,212 entitled, “Functional Color Selection System” discloses a system for automatically generating a palette of coordinated, harmonious, and aesthetically pleasing colors by symmetrically manipulating colorimetrically specified colors in a perceptually uniform color space. Specifically, a user selects a single “key color” which the color selection system then uses to generate one or more “analogous harmony” colors all of which reside on a single plane in the color space. The method used to select harmonizing colors is described with reference to FIG. 5. In addition to the system selecting harmonizing colors, it is also able to generate contrasting harmonies, as described with reference to FIG. 6, and lightness and chroma variation colors as described with reference to FIG. 8. Also, the user may vary the hue of the entire palette by a fixed amount to view the harmonious palette in different hues. The method described in this patent improves upon the method of the U.S. Pat. No. 4,794,382 patent in that a perceptually uniform color space from which colors are selected is employed. While existing perceptually uniform color spaces have been designed to exhibit colors that are related to each other in an organized and logical manner, from the perspective of the human eye, the relationships between the colors in existing perceptual color spaces, such as the Munsell or CIELAB color spaces, are not as consistent as they need to be in order for computer software to accurately measure contrast between colors which is a requirement for generating accurate color palettes. Another limitation of the method disclosed by the -212 patent is that all of the colors on any of the individual palettes created by this color selection system reside in a single plane in the color space, therefore only providing the artist with a two-dimensional solution which artificially limits the color selection process.
U.S. Pat. No. 6,081,253 entitled, “Method for Generating Numerous Harmonious Color Palettes from Two Colors” discloses method for the creation of color palettes based on the initial selection by the artist of two colors from a perceptual color space, such as CIELAB. The patent describes how to derive equations that define planes that pass through an axis formed by the two selected colors. The planes defined by the derived equations will always contain harmonious color groups since the natural, perceptual relationship between the colors on a plane is preserved.
U.S. Pat. No. 6,226,010 entitled, “Color Selection Tool” discloses a method for generating a blend of colors between two initially selected colors. Essentially, an artist selects an initial color and then selects another color at some distance from the initial color. The tool then generates the intermediate or blend colors that represents all of the colors in a straight line, assuming CIELAB color space, between the initially selected color and the first selected color. The artist can continue to select a second, third, etc. color at some distance from the initial color and create a palette of colors that is displayed in circular fashion as FIG. 1 illustrates.
Both of the methods for selecting colors for a color palette disclosed by the U.S. Pat. Nos. 6,081,253 and 6,226,010 patents suffer from the same limitations as the method of the U.S. Pat. No. 5,311,212, namely the inaccuracy injected into the process by the perceptual color spaces used and the limitation on the artist imposed by a two-dimensional color palette. The manner in which colors are selected for a palette in the prior art is further limited to a straight line between two colors or to a straight line of color with the selected color in the middle, or to a surface of color that cuts through the plane of a line described by two selected colors. The color harmonies generated for color palettes by these processes tend to be somewhat sparse and creatively confining therefore limiting the efficiency of the artist in the color selection process to the extent that they have to create a number of palettes in gain a full appreciation of the colors available to them. So, for instance, none of the prior art methods for color selection provide the artist with a tool to generate a palette of colors that are only some specified distance in tri-axial color space from a selected color. Still further, nowhere in the prior art is there a tool that provides the artist with a comprehensive and accurate means to automatically generate contrast relationships between a plurality of colors. More specifically, order and visual synchrony or harmony can be brought to any collection of colors by precisely controlling the range or proportional distances between those colors.
Therefore, it would greatly facilitate the process of selecting harmonically related colors if a color selection tool was available to artists that utilized a specially constructed, perceptually ordered color space that facilitates the automatic generation of a palette of colors with very precise contrast relationships. Further, a tool that permits the artist to precisely control contrast relationships between colors would be very useful during the creation of color palettes.